Cities are the crucibles of human history in which the future is forged. That is the message of the past two weeks, from the afterglow of Danny Boyle's rings on the retina of our imagination, to events in Aleppo, where tragically the only ceremonies are funerals. This tale of two cities, Europe's and Syria's largest respectively, has served to reinforce that most modern of tropes – the metropolis as the motor of progress. The director of the British Museum, Neil MacGregor, last week traced a lineage, perhaps only half tongue in cheek, from ancient Babylon to contemporary London, with Boris Johnson presumably cast as a beardless Nebuchadnezzar. Megamania – the obsession with size that the Shard, our modern Babel, crystallises – is undoubtedly the secular religion of a globalised elite. But are small cities the real unsung heroes of our times?

Nowhere is this more evident than in the Arab spring itself. The world's media, naturally enough, trained its lens on the region's capitals. But astute observers of the unfolding drama, like urbanist Deen Sharp, have pointed to the pivotal role played by the smaller cities in the region. The suicide of Tunisian street vendor Muhammed Bouazizi that sparked the region's first, "jasmine" revolution happened not in Tunis but in the peripheral city of Sidi Bouaziz four hours to the south. The first protests of the Egyptian revolution began not in Cairo but in Suez and Alexandria, while Benghazi's role as the epicentre of the Libyan revolution is unchallenged. In Syria meanwhile, it was another act of immolation far from the centre, this time in the mostly Christian city of Al-Hassakah (population 188,160) that was the spark for February's first "day of rage".

Capital cities are often the last bastions of any ancien regime . The vested interests and accumulated power of bureaucracies, both public and private, mean a nation's core can be as much a bulwark of conservatism as the bridge-head of change. In Britain, that most centralised of states, it was no accident that Chartist uprisings centred on Newport and Manchester, and in the 20th century the closest we came to revolution was in Liverpool and Glasgow. The role of small and medium-sized cities – like Leipzig and Dresden in East Germany and Timisoara in Romania in the revolutions of 1989 – was also surprisingly decisive.

That smaller cities punch way above their weight applies as much in culture and economics as in politics. As Richard Florida, the man who made economic geography cool, has pointed out, secondary cities are the giants of American music – Memphis's soul and rock'n'roll, then the grunge of pre-Microsoft-and-Starbucks Seattle, and nowadays Nashville, once just the capital of country, now the music industry's undisputed metropolis. Cities from the margins create breakthrough trends precisely because they are disconnected, outside the mainstream, fresh and authentic. London and New York can only ape these by creating "neighbourhoods", cities-within-the-city, with their own distinctive scene, like the cultural engines of Williamsburg or Shoreditch. But the easy commodification of metropolitan cultures means the hip is soon taken out of hipster.

The conventional wisdom that the largest cities are the drivers of innovation, both cultural and economic, doesn't stack up – certainly not as well as Brunel's chimneys. A recent McKinsey study found the common conception that massive megacities will dominate the horizons of the future to be fundamentally misplaced. It's the middleweight – some as small as 150,000 – not the mega cities that will contribute most to economic growth over the next 15 years, it concluded. This has certainly been a feature of the American recovery so far, where small to medium-sized cities, with populations of less than a million, accounted for 27 of the 30 metropolitan areas currently creating jobs at the fastest rate.

Small cities have proven fertile territory for new industries, or startups that challenge incumbents. The success of Warren Buffet's investment conglomerate Berkshire Hathaway is partly a result of its insulation from Wall Street in far-flung Omaha, Nebraska. San Antonio, Texas was a much better fit for web-hosting giant Rackspace than Silicon Valley would ever be in building a business based fundamentally not on tech, but on service which needs the employee retention smaller cities excel at. Gazelle-like cities like Raleigh, North Carolina and Austin, Texas – another cultural success story – have outstripped the rest of the US in both population and GDP growth. Minneapolis, as Harvard economist Ed Glaeser has written, was all but written off by 1980 but local startups like megaretailer Target have helped transform it into the wealthiest metropolitan area in the Mid West. As local band The Small Cities opine, "home is where the start is".

In the UK, examples may be a little harder to come by. Cardiff is home to the insurer Admiral, and Newcastle has Sage, but the dominance of the City of London – the clue is in the title – may be choking off the natural entrepreneurialism of Britain's mighty middleweights. Nevertheless even here people are beginning to vote with their feet. While London with its 12% growth in population size since 2001 got all the headlines (it's where they are written after all) – it was Manchester that topped the table with an incredible 20% surge in the number of Mancunians. People like their cities, it seems, the way they like their Kindle: bright and compact. The BBC has seen the light. Maybe it's time even the Manchester Guardian went home.